The US president and first lady Jill Biden will travel to Arlington, Virginia, for the service on Monday, after an appearance at commemoration service in New Castle not far from Wilmington, Delaware, on Sunday.
The service fell six years to the day that Beau Biden — a former army officer and US attorney — died of brain cancer aged 46. A heavy but defining loss for the elder Mr Biden.
Mr Biden spoke frequently and emotionally in front of Delaware military families of his son, while thanking others for their sacrifices, during the service.
“I can’t thank you enough for the continued service for the country,” said Mr Biden. “I know how much the loss hurts.”
“They’re the guardians of us and we’re the guardians of their legacy, [and] despite all the pain, I know the pride you feel in the loved one you have lost.”
Mr Biden added that US veterans and troops were “the very best of what America has to offer”.
The US president also told a story of how Beau, who served in Delaware’s National Guard before deployment to Iraq, wore a uniform emblazoned with a different surname to avoid special treatment.
The story — told for the first time on Friday at a military base in Virginia — was one of a number of personal moments for Mr Biden during the Memorial Day weekend, featuring Beau.
His late son is expected to be referred to during Monday’s ceremony at the Arlington National Cemetery, commemorating all those who died in US military service.
Following the service on Sunday, Mr Biden and first lady Dr Biden laid a wreath at the memorial in Delaware, as the two have done for decades, and attended a mass for Beau.
Beau Biden served two terms as Delaware’s attorney general before declaring a run for governor, and many saw in him the same aspirations that brought his father to the White House.
Additional reporting by Associated Press